Soapstock treatment

Abstract

A method for the recovery of fatty acids comprising a salt of the fatty acid is disclosed. The method comprises the steps of: (a) reacting the salt of the fatty acid with CO 2 and with a reagent other than hydroxide and selected from a group of compounds carrying at least one of O—H, N—H, S—H, C—O—C and C—O—N moieties, to form a reaction mixture comprising at least one of a carbonate and a bicarbonate and a product selected from fatty acids and derivatives thereof, and (b) separating the product from the reaction mixture. A method for the production of fatty acid ester from free fatty acid of crude vegetable oil is also disclosed. A free fatty acid that is substantially free of emulsifier is also disclosed.

1 . A method for the recovery of fatty acids comprising a salt of the fatty acid, the method comprising the steps of: (a) reacting the salt of the fatty acid with CO 2  and with a reagent other than hydroxide and selected from a group of compounds carrying at least one of O—H, N—H, S—H, C—O—C and C—O—N moieties, to form a reaction mixture comprising at least one of a carbonate and a bicarbonate and a product selected from fatty acids and derivatives thereof, and (b) separating the product from the reaction mixture. 
   
   
       2 . The method of  claim 1 , wherein the reagent is selected from a group consisting of water, alkanols, esters and combinations thereof. 
   
   
       3 . The method of  claim 1 , wherein the product comprises at least one of free fatty acids and fatty acid esters. 
   
   
       4 . The method of  claim 1 , wherein a cation of the salt of the fatty acid is selected from a group of cations of ammonia, alkali and alkaline earth metals and combinations thereof. 
   
   
       5 . The method of  claim 1 , wherein the salt of the fatty acid comprises a product of a vegetable oil refining process. 
   
   
       6 . The method of  claim 1 , wherein the salt of the fatty acid comprises a soapstock of a vegetable oil refining process. 
   
   
       7 . The method of  claim 6 , wherein the vegetable oil refining process is selected from a group consisting soybean oil, rapeseed oil, sunflower oil and combinations thereof. 
   
   
       8 . The method of  claim 1 , wherein a partial vapor pressure of the CO 2  is greater than about 1 Kg/m 2  during at least a portion of duration of the reaction. 
   
   
       9 . The method of  claim 1 , wherein the reaction with CO 2  is conducted substantially in the absence of a water-insoluble base. 
   
   
       10 . The method of  claim 1 , wherein the reaction with CO 2  is conducted in the presence of at least one of water, vegetable oil and organic solvents. 
   
   
       11 . The method of  claim 10 , wherein the reaction with CO 2  is conducted in the presence of water. 
   
   
       12 . The method of  claim 11 , wherein the water to salt weight ratio is in a range of between about 0.1 and about 100. 
   
   
       13 . The method of  claim 10 , wherein both water and vegetable oil are present and wherein the water to oil weight ratio is in a range of between about 1 and about 20. 
   
   
       14 . The method of  claim 11 , wherein the reaction with CO 2  is conducted at a temperature of between about 0 C and about 95 C. 
   
   
       15 . The method of  claim 11 , wherein the reaction with CO 2  is conducted in a multiple-stage counter-current mode, which is fed at least one of water and an aqueous solution on one side and the salt of the fatty acid on the other. 
   
   
       16 . The method of  claim 11 , wherein the alt of the fatty acid is a product of vegetable oil refining, wherein such refining comprises a step of washing with water or with an aqueous solution an alkali-treated oil, and wherein the water present in the reaction results, at least partially, from wash of alkali-treated oil. 
   
   
       17 . The method of  claim 11 , wherein the product is a free fatty acid. 
   
   
       18 . The method of  claim 1 , wherein the separation of the product comprises at least one of solvent extraction, distillation, and gravimetric separation. 
   
   
       19 . The method of  claim 1 , wherein the separation of the product uses solvent extraction and the solvent used is a vegetable oil. 
   
   
       20 . The method of  claim 1 , further comprising the step of separating by distillation the product from a solvent comprising the vegetable oil. 
   
   
       21 . The method of  claim 1 , wherein the product is a free fatty acid and wherein a fatty acid solution in the alkanol is formed. 
   
   
       22 . The method of  claim 21 , wherein the fatty acid in the alkanol solution is reacted to form the ester of the fatty acid with the alkanol. 
   
   
       23 . The method of  claim 1 , further comprising the step of separating at least one of the formed carbonate and the bicarbonate to form at least one of carbonate and bicarbonate product. 
   
   
       24 . The method of  claim 23 , wherein at least one of the formed carbonate and bicarbonate product is used for alkali treatment of crude vegetable oil. 
   
   
       25 . The method of  claim 24 , wherein the bicarbonate product is converted to carbonate product prior to the use in alkali treatment of crude vegetable oil. 
   
   
       26 . The method of  claim 24 , wherein the at least one of the formed carbonate and bicarbonate product is an aqueous solution, further comprising a step of concentrating the aqueous solution by methods comprising at least one of reverse osmosis, water evaporation, and combinations thereof. 
   
   
       27 . The method of  claim 24 , further comprising a step of bleeding an aqueous solution in order to avoid substantial build up of impurities. 
   
   
       28 . The method of  claim 27 , wherein bleeding and reacting with CO 2  are conducted substantially simultaneously. 
   
   
       29 . The method of  claim 1 , wherein the feed stream contains at least one of phospholipid and its derivatives and wherein at least one of phospholipid and the derivatives is hydrolyzed before the reaction with CO 2  or simultaneously with it. 
   
   
       30 . The method of  claim 1 , wherein the reagent is an alkanol and the product is an ester of the alkanol. 
   
   
       31 . The method of  claim 1 , wherein the reagent is methanol and the reaction product is a fatty acid methyl ester. 
   
   
       32 . The method of  claim 24  or  25 , wherein CO 2  formed is collected and used in the reaction of step (a). 
   
   
       33 . The method of  claim 32 , wherein the collected CO 2  is compressed prior to the use in the reaction of step (a). 
   
   
       34 . The method of  claim 1 , wherein reacting with CO 2  does not reach completion so that the reaction mixture comprises unreacted fatty acid salts. 
   
   
       35 . The method of  claim 34 , further comprising a step of separating unreacted fatty acid salts. 
   
   
       36 . The method of  claim 35 , wherein at least a fraction of the separated unreacted fatty acid salts is recycled to the reaction. 
   
   
       37 . The method of  claim 1 , wherein the salt of the fatty acid comprises vegetable oil, and further comprising a step of separating the vegetable oil from the reaction mixture to form a separated vegetable oil stream. 
   
   
       38 . The method of  claim 37 , wherein the separated vegetable oil stream is combined with crude vegetable oil as such or after pretreatment. 
   
   
       39 . A method for the production of fatty acid ester from free fatty acid of crude vegetable oil, comprising the steps of: (a) treating the crude vegetable oil with at least one of bicarbonate and carbonate to form a salt of the fatty acid; (b) separating the salt of the fatty acid from the crude vegetable oil to form a fatty-acid-depleted vegetable oil and a fatty-acid-salt-containing soapstock; (c) reacting the salt of the fatty acid with CO 2  and an alkanol to form a reaction mixture comprising a fatty acid ester and at least one of bicarbonate and carbonate of the cation of the salt; (d) separating the ester from the reaction mixture; (e) separating the at least one bicarbonate and the carbonate from the reaction mixture; and (f) using at least a fraction of the separated at least one of bicarbonate and carbonate in the treatment of step (a). 
   
   
       40 . A free fatty acid that is substantially free of emulsifier, produced by the process of: (a) reacting a salt of the fatty acid with CO 2  and with a reagent other than hydroxide and selected from a group of compounds carrying at least one of O—H, N—H, S—H, C—O—C and C—O—N moieties, to form a reaction mixture comprising at least one of a carbonate and a bicarbonate and the free fatty acid, and (b) separating the free fatty acid from the reaction mixture. 
   
   
       41 . The free fatty acid of  claim 40  wherein the emulsifier is at least one of a gum and a non-hydratable phosphatide.